Moorlach, a Republican, first hinted at his candidacy in July after ruling out a run for governor against incumbent Jerry Brown. In January, he will be termed out of the Board of Supervisors, where he represents District 2, which includes Costa Mesa, Huntington Beach and Newport Beach.

State Sen. Mimi Walters (R-Laguna Niguel), Republican Marine veteran and former commercial airline pilot Greg Raths of Mission Viejo and Democratic businessman Drew Leavens, who lives in Irvine, are left vying for the seat, according to the Orange County registrar of voters.

Moorlach, who lives in Costa Mesa, said in a statement emailed to supporters Monday evening that he still felt he was the best candidate for the spot and that polling showed he was leading the pack.

"But without satisfactory resources in the bank," he wrote, "I will find myself being hammered by negative mail on a weekly basis."

Tuesday, he added that it was tough to call friends "with five minutes to ask for money," rather than to catch up.

The longtime Costa Mesa resident gained political recognition in 1994 when he raised concerns about the vulnerability of Orange County's investment pool during his campaign for county treasurer. The county declared bankruptcy later that year.

He was first elected to the board of supervisors in 2006.

Ultimately, he said, his bookish accountant's nature won out over a life on the campaign trail.

"I'm more of a worker bee than a social bee," he said.

In the statement, he thanked those who had helped him over the past two decades at the county level.

"I will enjoy my final year as supervisor and then return to the private sector, grateful for the opportunity to have served this wonderful county and its 3 million residents," he wrote. "I've been blessed."